1. Field of the Invention
The present invention relates to an inner-rotor motor in which a stator includes a plurality of stator segments. In particular, the present invention relates to a wiring configuration of a stator.
2. Description of the Related Art
In general, motors have a variety of potential performance levels that are varied depending on the intended purposes of the motors. The number of poles of a rotor, the number of slots of the stator, the direction of the winding of coils, the arrangement of the coils, and so on are designed in accordance with a desired performance of the motor. Thus, there are a large variety of wiring configurations available for motors.
For instance, referring to FIG. 1A, in an 8-pole 12-slot motor, a group of four coils connected in parallel may be provided for each of a U phase, a V phase, and a W phase. Moreover, the groups of coils for the respective phases may be connected in a Y configuration. A wiring configuration in which groups of coils connected in parallel are connected in the Y configuration will be referred to as “parallel connection”.
Meanwhile, a wiring configuration different from the parallel connection may be adopted for a 14-pole 12-slot motor. Specifically, referring to FIG. 1B, two coils are connected in series to define a sub-coil group. Winding directions of the two coils connected in series are opposite to each other. Two sub-coil groups are connected in parallel to define a group of coils for each of the U phase, the V phase, and the W phase, and the groups of coils for the respective phases are connected in the Y configuration. A wiring configuration in which sub-coil groups, each of which is made up of a group of coils connected in series, are used will be referred to as “series-parallel connection”.
As described above, different types of motors, even motors having the same number of slots, may have greatly different wiring configurations depending on the motor design thereof. Therefore, production equipment, such as a winding machine and so on, and a manufacturing procedure need to be suitably arranged for each type of motor. This presents an impediment to improving productivity.
Thus, a variety of configurations have been conceived to improve the productivity (see, for example, JP-A 2006-50690 and JP-A 2007-244008).
JP-A 2006-50690 discloses a stator in which a plurality of coils which are continuously wound are arranged to have the same winding direction in order to facilitate a winding operation for the coils which are continuously wound.
JP-A 2007-244008 discloses a rotary electrical machine including a power supply portion. The power supply portion includes a plurality of conductive members, each of which is arranged to connect coils to one another, and a holding member arranged to hold the plurality of conductive members. The power supply portion is configured so as to be compatible with a plurality of different wiring configurations, such as the Y configuration and a delta configuration. Specifically, the holding member includes four concentric common grooves defined therein. In addition, conductive members for the U phase, the V phase, and the W phase, a conductive member for common use, and so on are fitted in the common grooves.
JP-A 2009-017666 discloses a motor in which busbars are held in an insulator (JP-A 2009-017666).
However, in the cylindrical stator of the motor described in Japanese Patent No. 4281733, circumferential side surfaces of the resin covers of the stator segments are arranged to be in contact with one another. Therefore, it is difficult to allow the stator to have a sufficient degree of circularity for some specific purposes.